KR20230104098A - Fluidic assembly carrier system for mass transition of micro-light emitting diodes and method for mass transition of micro-light emitting diodes - Google Patents

Abstract

A fluidic assembly carrier system for mass transition of micro-light emitting diodes includes a fluid assembly carrier substrate having a planar upper surface and an array of collection positions formed on the upper surface of the carrier substrate. At each of the collection positions, a concave well is configured to temporarily hold one fluid-deposited micro light emitting diode.

Description

Fluid assembly carrier system for mass transfer of micro light emitting diodes and method for mass transfer of micro light emitting diodes

The present application relates to the field of micro-light emitting diode (micro-LED) displays, and in particular, to a system and method for mass transition of micro-light emitting diodes in a display manufacturing process.

A red-green-blue (RGB) display is composed of a plurality of pixels, and these pixels emit light of three wavelengths corresponding to red light, green light, and blue light among visible light. The RGB parts of these pixels (each part is referred to as a sub-pixel) are turned on and overlapped in a systematized manner to create colors in the visible light spectrum. Different displays have different ways of creating RGB images. Liquid Crystal Displays (LCDs), currently the most popular technology, use a white light source (usually a white LED that emits fluorescence) to illuminate the color filters of subpixels to create an RGB image. Light having some wavelengths included in the white light is absorbed, and light having some other wavelengths is transmitted through the color filter. Therefore, the efficiency of one LCD display can be lower than 4%, and its contrast is limited by the light leaking from the liquid crystal cell. An Organic Light Emitting Diode (OLED) display excites the organic light emitting material of each subpixel to emit light having a corresponding wavelength, thereby generating RGB light rays. Since the OLED pixels are directly emitting light, the contrast of the display is relatively high, but the organic material deteriorates over time, resulting in image aging.

The third technology, namely the display technology referred to in this application, is a micro light emitting diode display, which directly emits light using micro (body diameter of 5 to 150 micrometers (μm)) inorganic LEDs as sub-pixels. Inorganic micro light emitting diode displays have many advantages over other displays: compared to LCD displays, micro light emitting diode displays have a contrast exceeding 50,000:1 and higher efficiency. Unlike OLED displays, inorganic LEDs do not suffer from aging, and the attainable luminance is remarkably high.

In today's mainstream High Definition Television (HDTV), standard resolution televisions have 2 million pixels (or 6 million subpixels), while the higher resolution 4K and 8K standards have 8 million and 33 million pixels, respectively. have pixels. Although tablet PCs and mobile phones use relatively small display screens, they have millions of pixels, and the resolution of their display screens exceeds 600 pixels per inch (ppi). Accordingly, manufacturing of a display screen using micro light emitting diodes requires assembling a large-scale micro light emitting diode array having different pixel intervals at a relatively low cost, and thus displays having various sizes and resolutions can be manufactured. As described below, the most traditional micro light emitting diode array assembly technology is called a pick-and-place technology because each micro light emitting diode is independently picked up from a carrier and placed on a substrate. Since each micro light emitting diode is processed independently, the assembly process is very slow.

1A to 1C are cross-sectional views of stacked LEDs based on Gallium Nitride (GaN) (FIG. 1A), cross-sectional views of two completely fabricated vertical micro-light emitting diodes (FIG. 1B), and surface-mounted micro-light emitting diodes (prior art). ) is a cross-sectional view (Fig. 1c). Since GaN-based high-brightness LEDs, which are widely used in general lighting, form a complex manufacturing system, micro light emitting diodes for display applications are based on existing investments in the industry. GaN-based LEDs emitting blue (about 440 nanometers (nm)) wavelengths are fabricated in a series of complex high-temperature metal organic chemical vapor deposition (MOCVD) steps, resulting in the vertical LED structure shown in cross section in FIG. 1A. The fabrication process is performed on polished sapphire, silicon or silicon carbide (SiC) substrates with a diameter of 50 to 200 millimeters (mm). By depositing undoped GaN and optionally depositing an aluminum nitride (AlN) buffer layer to prepare the surface, a crystal lattice surface with small defects and a GaN lattice constant is created. It is necessary to compensate for the crystal lattice mismatch between the substrate and GaN by adjusting the initially deposited thickness and temperature. In other words, since the surface quality must be improved by increasing the thickness, the thickness of the high-efficiency device is greater than 3 μm on both sides. Since the MOCVD deposition process is complex and expensive, it is very important to optimize the micro light emitting diode process to effectively utilize the full area of the growth wafer.

After forming the crystalline GaN surface through initial growth, silicon doping is added to form the first LED layer, thereby forming n ⁺ GaN used for the cathode. Optionally, the stack may include a layer adjusted for electron injection and hole blocking. Subsequently, the deposition has a multiple quantum well (MQW) structure in which gallium indium nitride (InxGa1-xN) and GaN are stacked alternately with each other, where the indium content and the thickness of the layer determine the emission wavelength of the device . An increase in the indium content causes the emission peak to shift toward longer wavelengths, but increases the stress generated due to crystal lattice mismatch, so that a high-efficiency GaN device for emitting red light cannot be fabricated, and the efficiency of green light LEDs is not as good as blue light. lower than that of LEDs. After forming the MQW, the layered structure may further include a layer adjusted for electron blocking and hole injection. The MOCVD layer sequence is completed by depositing GaN doped with magnesium (Mg) to form a p ⁺ anode layer.

Since the LEDs used in general lighting (up to 3-4 mm on each side) are much larger than the micro-light emitting diodes (diameter 5-150 μm) applied in micro light emitting diode displays, both patterning and electrode requirements are obvious. different. Micro light emitting diodes must be bound to the substrate electrodes using welding material or asymmetric electrically conductive film (ACF), while large LEDs are usually bound through lead wires or bound to the lead wire frame through solder paste. . Since the volume of the micro light emitting diode is very small, by removing most of the area of the MOCVD wafer during the patterning process, the usable light emitting area of each wafer is reduced. Since LED wafers are relatively expensive, and the high resolution required for manufacturing micro light emitting diodes further increases the cost, it is very important to reduce the material cost of the micro light emitting diode display as much as possible by using the light emitting area as effectively as possible.

In the simplest process, a thin layer of nickel oxide (NiO _X ) (a few nanometers) is deposited to match the p ⁺ GaN work function, followed by one layer of indium tin oxide (ITO) with a thickness of 50-300 nm. ) to form a transparent conductive electrode on the MOCVD stack. Next, the deposited stack structure is patterned and etched, and a single micro light emitting diode having the smallest actual size and spacing is generally used by a reactive ion etching (RIE) process based on nitrogen gas (Cl ₂ ). generate In particular, in the case of highly efficient production of micro light emitting diodes, since the thickness of the LED structure is only 3 to 5 μm, the thickness of the LED structure limits the minimum space that can be successfully etched.

As illustrated in FIG. 1C , after the periphery of the LED is etched, additional processing is performed to form an electrode on the anode. In order to prevent leakage and etch an opening for connecting the ITO layer, a passivation layer is generally prepared, but the passivation layer is generally plasma-enhanced chemical vapor deposition (PECVD) silica (Silicon Dioxide, It is formed by SiO ₂ ) or optionally includes a thin atomic layer deposition (ALD) alumina (Aluminum Oxide, Al ₂ O ₃ ) layer provided on the surface. The anode structure is completed by depositing an electrode stack structure, and the electrode stack structure includes a material such as indium/tin (In/Sn) or gold or germanium (Au/Ge) alloy.

2A shows a process of removing a micro light emitting diode from a sapphire substrate through laser lift off (LLO). 2B illustrates a pick-and-place process of moving a device from a carrier wafer and placing it on a display substrate. Figure 2c shows the connection (prior art) of the micro light emitting diode anode and the substrate electrode. Specifically, in FIG. 2A , the fabricated micro light emitting diode is bound to a carrier wafer through an adhesive layer and simultaneously removed from a sapphire substrate through laser peeling. In FIG. 2B , after a micro light emitting diode is removed from a carrier through a pickup head, it is placed on a subpixel, and an anode thereof is electrically connected to a corresponding electrode of a substrate. The pixel is completed by coating a dielectric suitable for the micro light emitting diode (eg, polyimide capable of photolithography for a pattern), and at the same time, the cathode of the micro light emitting diode is connected to the electrode of the substrate. Metal interconnects are deposited and patterned to form connections as shown in FIG. 2C.

LEDs that emit red light with a wavelength of about 630 nm are generally made of aluminum gallium indium phosphide (AlGaInP) grown on gallium arsenide (GaAs), and since GaAs is not transparent, laser ablation technology is used to remove them from the GaAs substrate. The LED cannot be peeled off. Therefore, when the red light LED is to be separated from the substrate, the substrate is completely etched or selectively etched (typically hydrogen chloride (HCl): acetic acid is used) to undercut the substrate and then the LED is peeled off. The dimensions (cross-section) of the LEDs are similar to GaN general-purpose lighting LEDs (sizes range from 150 to 1000 μm). U.S. Patent 10,804,426 fully describes the AlGaInP LED process, which patent is incorporated herein by reference.

The pick-and-place assembly process described above has some significant problems, namely high cost and low output. Specifically, since the assembling process is essentially performed in series, it takes a very long time and costs a lot when assembling millions of micro light emitting diodes. The small size of the micro light emitting diode itself makes it difficult to manufacture a grip device such as a grip head, and the edge of the grip device may interfere with an adjacent micro light emitting diode during the gripping process or interfere with a reflector structure between pixels during the assembly process. . The single pick and place method described above can be extended to a parallel process by simultaneously gripping and transferring multiple micro light emitting diodes using a mass transfer head. However, this mass transfer method can be of very low quality if there are defective devices in a group of micro light emitting diodes that are simultaneously transferred, and the spacing between each micro light emitting diode depends on the spacing of the devices grown on the wafer. determined by

3A-3H show an example (prior art) of one mass transfer method. The mass transfer method is a method of transferring a plurality of micro light emitting diodes arranged in an array to a display substrate as a whole, and has been widely developed to solve the problem of low throughput of serial pick-and-place assembly. In the simplest quality transfer process, a rectangular imprint stamp picks up one rectangular micro light emitting diode array from a carrier and presses the micro light emitting diode to a display substrate, so that each micro light emitting diode is coupled to a corresponding electrode. Since micro light emitting diodes of different colors must be considered in manufacturing an RGB display, the transfer imprint stamp provides space for micro light emitting diodes of the other two subpixel colors by picking up once every three micro light emitting diodes. In the case of the surface-mounted micro light emitting diode shown in FIG. 2C, the assembling process proceeds according to the following sequence.

1) Independent MOCVD wafers are prepared for micro light emitting diodes of various colors, and each micro light emitting diode has an appropriate size and spacing. A gap between adjacent micro light emitting diodes is referred to as a gap. See FIG. 3A. Each micro light emitting diode has one cathode and one anode for connection to the display board. The micro light emitting diode array is removed from the growth wafer by laser ablation and held on a carrier substrate (not shown).

2) Since a plurality of groups of cathode electrodes and anode electrodes are provided on the display substrate (FIG. 3B), and the distance between the electrodes of each group is a plurality of times the distance between the respective micro light emitting diodes of the wafer, the electrode and the transfer imprint stamp Positions of the micro light emitting diodes are matched with each other. This interval determines the final resolution of the display. The electrode may be a solder such as copper, indium tin oxide/aluminum (ITO/Al), gold or tin/indium (Sn/In). An ACF film may be used to cover the electrode. By determining the materials of the electrodes of the display panel and the micro light emitting diode, an ohmic contact is formed through a subsequent binding process of step 5) below.

3) An imprint stamp is prepared according to the position where the pickup point and the subpixel spacing of the display match. Currently, pick-up mechanisms applied to fix each micro light emitting diode include elastic bodies, tapes, static electricity and magnetic fields. Although FIG. 3C shows one imprint stamp having a size of 3*3 pixels, hundreds of pixels are usually mounted on an actual imprint stamp.

4) Referring to FIG. 3D, the imprint stamp and the carrier substrate on which the micro light emitting diodes of the first color are loaded are aligned and positioned, and the imprint stamp and the carrier substrate are brought into contact with each other so that the fixing structure grips the plurality of micro light emitting diodes. Remove from the carrier substrate.

5) Referring to FIG. 3E , the charged imprint stamp and the electrodes of the first group of display substrates are aligned and positioned.

6) Referring to FIG. 3F, the imprint stamp is compressed and brought into contact with the display substrate, and generally heated simultaneously to form a binding structure between the micro light emitting diode electrode and the electrode of the display substrate. After binding is formed and sufficiently cooled to fix the micro light emitting diode, the imprint stamp is removed to reuse it.

7) As shown in Figs. 3G to 3H, the same operation is performed for the micro light emitting diodes of the second color and the third color, respectively, to form an RGB display array.

Although the mass transfer method can be assembled and applied to the manufacture of displays, some problems such as low product yield and high product cost still exist. First, in FIG. 3B, the display spacing in the x-direction and the y-direction is only an integer multiple of the spacing between the micro light emitting diodes of the MOCVD wafer, and the case of 3*2 is illustrated in the drawing. Since complete display manufacturing technology must be able to manufacture screens of different sizes that meet industry standards, for example, 4K (3840 * 2160 pixels), technology that can change the spacing of micro light emitting diodes in the imprint stamp (interval scalable technology). It is also possible to customize the size of the micro light emitting diodes of the MOCVD wafer for the size and resolution of each display, but this increases unnecessary cost. Next, the pick-up device must obtain a size balance of connection strength, and if the connection strength is too small, some micro light emitting diodes cannot be separated from the carrier substrate, and gaps are formed in the array. Conversely, if the connection strength is too great, the micro light emitting diode is forcibly removed after being welded to the substrate. In both of the above cases, the luminance of the subpixel is reduced, so the display does not allow it. Finally, the structure of the transfer imprint stamp is complex and difficult to manufacture. In order to prevent the imprint stamp from interfering with the adjacent micro light emitting diodes, the connection point must be smaller than the distance between the micro light emitting diodes. This is very difficult to implement in complex fixation methods that must generate local fields (e.g., static or magnetic forces). Since the imprint stamp is easily contaminated and damaged, and especially an imprint stamp made of an elastic material such as polydimethylsiloxane (PDMS) is easily contaminated and damaged, it is also very important how to effectively clean and reuse the imprint stamp.

To illustrate the deficiencies of the mass transfer imprint process, Figure 3h describes several possible failure situations.

Fault a: When picking up, the adhesion of the imprint stamp is poor, resulting in insufficient micro light emitting diodes;

Failure b: contamination of the imprint stamp caused misplacement of the micro light emitting diode;

Failure c: Particles are produced due to transfer imprint stamp contamination;

Failure d: The micro light emitting diode is broken;

Fault e: Micro light emitting diode short circuit occurs due to a defect in the MOCVD process;

Failure f: The micro light emitting diode is forcibly removed by the imprint stamp and the electrode is damaged.

4A and 4B imprint and cover an exemplary area picked up using a 14 mm imprint stamp (FIG. 4A) on a 100 mm wafer. Here, 20% of micro light emitting diodes ultimately remain on the wafer, and defective micro light emitting diodes exist in three imprint stamps. Another limitation of the quality transfer process is the restriction of the rectangular shape of the imprint stamp, which does not match the prototype wafer for producing LEDs by MOCVD. Figure 4a shows an arrangement situation when using a 14*14 mm imprint stamp on a typical 100 mm wafer. Using a large area imprint stamp can improve assembly speed, instead leaving more micro light emitting diodes on the growth wafer. Since the requirement to fill all the imprint stamps has to be satisfied, there are large areas of the wafer where the imprint stamps cannot be used. In the above example, the quality-approved but discarded micro light-emitting diodes account for about 20% of the total number, which directly increases the cost. In addition, in the case of a defective micro light emitting diode, the affected imprint stamp must be restored or discarded. In the above example, three defects are randomly described for illustrative purposes only. If the defective imprint stamp is discarded in the example, only about 70% of the initial micro light emitting diode can be used for manufacturing the display.

The mass transfer method has a significant advantage, that is, since the binding process proceeds with pressure applied to the micro light emitting diode, a good mechanical contact is formed between the two bonding electrodes. This ensures that large area contacts are formed between the electrodes. The mechanical contact breaks down the insulating oxide on the surface, improving the wettability of the welding material. In order to form a hard contact between the conductive filling material and the micro light emitting diode and the electrode on the display substrate, pressure is required for ACF bonding as well.

It would be advantageous if there was a structure and method capable of charging a carrier substrate realizing mass transfer assembly of micro light emitting diode displays and improving assembly smoothness and yield in the following manner.

1. Arbitrary display resolution can be achieved through simple spacing expansion;

2. A micro light emitting diode (known as an excellent chip) can be produced that does not have a series of equipment defects such as missing, broken or short-circuited;

3. The assembly speed of mass transfer can be improved by charging and transferring the imprint stamp through a massive parallel transfer method;

4. It uses a simple transfer imprint stamp, so the manufacturing cost is low, and it can be reused through strong cleaning;

5. A simple imprint mechanism that does not damage the display substrate can be used;

6. The remaining micro light emitting diodes can be retrieved from the defective imprint stamp.

The fluid assembly carrier system for mass transfer of micro light emitting diodes of the present application includes a fluid assembly carrier substrate having a planar upper surface and an array of collecting positions formed on the upper surface of the carrier substrate, each of the collecting positions A concave well is configured to temporarily fix one fluid deposited micro light emitting diode.

In the micro light emitting diode mass transfer method of the present application, manufacturing micro light emitting diodes on a wafer, discharging the micro light emitting diodes from the wafer as a suspension, and transferring the micro light emitting diodes to the carrier substrate by fluid deposition. transferring the micro light emitting diodes from the carrier substrate to the mass transfer imprint stamp, and transferring the micro light emitting diodes from the mass transfer imprint stamp to a display substrate.

The present application provides a method and related structure for fabricating a micro light emitting diode array on a carrier substrate or transfer imprint stamp via fluid assembly. The assembled micro light emitting diode can be applied to a display substrate and can be bound through a mass transfer method. Micro light emitting diodes are fabricated on wafers through traditional MOCVD methods, and their shapes are selected in a style that allows for easy fluid assembly and imprinting on display substrates.

Accordingly, the present application provides a micro light emitting diode mass transfer imprint system, which includes an imprint stamp substrate having an upper surface. On the upper surface, an array of catch positions for imprint stamp substrates are formed, and columnar grooves for temporarily fixing keels extending from the bottom surface of the micro light emitting diodes are all installed at each of the capture positions. When a micro light emitting diode is a surface mount type, it has a flat upper surface, and the flat upper surface includes a first electrode and a second electrode. When the micro light emitting diode is a vertical type, it has a flat top surface, and the planar top surface includes a first electrode. In this case, the pillar is a second electrode that conducts electricity. The imprint system further includes a fluid-assembled carrier substrate, wherein an array of wells is formed on a planar upper surface of the carrier substrate, and the array of wells has a gap separating adjacent wells, the gap being the gap between the imprinted wells. It is matched with the spacing of the adjacent capture positions on the stamp substrate.

A related micro light emitting diode mass transfer method includes providing a fluid assembled carrier substrate having an array of wells, and providing the imprinted stamp substrate, wherein at each capture location in the array, a well and a well of the carrier substrate are provided. Columnar grooves matching each other are configured. This method allows micro light emitting diodes to be filled into wells of the carrier substrate by using a fluid assembly process. This method transfers the micro light emitting diode from the carrier substrate to the imprint stamp substrate by pressing the upper surface of the imprint stamp substrate to the upper surface of the carrier substrate so that each of the capture positions corresponds to a corresponding well. The grooves of each capture position load the pillars extending from the bottom surface of the micro light emitting diode, restrain the pillars, and fix the micro light emitting diodes to the imprint stamp substrate. Since the use of a carrier substrate removes the limitation due to the spacing between the micro light emitting diodes of the MOCVD wafer, it allows various imprint stamp substrate spacing to be applied to different display substrate sizes and resolutions.

The method further provides a display substrate having an array of micro light emitting diode connection gaskets, wherein each micro light emitting diode connection gasket includes at least one electrode formed on an upper surface, the electrode having lower column and row control lines. is electrically connected to the matrix of The connection gasket has an interval separating adjacent locations, and the interval matches the interval between adjacent capturing locations in the imprint stamp substrate. In this method, the upper surface of the imprint stamp substrate is pressed against the upper surface of the display substrate, so that each capture position is connected to the corresponding micro light emitting diode position, and a plurality of micro light emitting diodes are connected from the imprint stamp substrate to a plurality of connecting gaskets of the display substrate. transition to On the other hand, the step of transferring the micro light emitting diodes to the connection gasket of the display substrate includes heating the display substrate to bind the plurality of micro light emitting diodes to the plurality of connection gaskets. When RGB is displayed, this method sequentially presses the imprint stamp substrate on which the micro light emitting diode of the first wavelength, the micro light emitting diode of the second wavelength, and the micro light emitting diode of the third wavelength are installed at the capture position, or one An independent imprint stamp substrate may correspond to a micro light emitting diode of one wavelength.

The present application further provides a micro light emitting diode mass transfer method, wherein the method uses a fluid assembly imprint stamp substrate having a planar top surface, the top surface having a first peripheral shape, depth and a planar bottom surface. A number of capture sites are formed. Through the fluid assembly process, the capture location can be filled with a micro light emitting diode having a first peripheral shape, the micro light emitting diode having a thickness greater than the depth of the capture location, a lower surface in contact with the lower surface of the capture location, and a flat surface. It has a top surface made of and a first electrode extending from the catching position and one fixing mechanism. On the other hand, the fixing mechanism is a pillar formed on the upper surface of the micro light emitting diode, the pillar may be a pillar that conducts electricity connected to the first electrode, and is removed after the micro light emitting diode is fixed to the imprint stamp substrate. It can also be a temporary pillar that does not conduct electricity. On the other hand, the fixture is a first component including a conjugated bio molecule pair installed on the lower surface of each micro light emitting diode. In this case, the second component including the conjugated biomolecule pair is provided on the lower surface of each capture site.

As described above, the method provides a display substrate having a planar top surface and an array of micro light emitting diode connection gaskets, each micro light emitting diode connection gasket including a first electrode formed on the top surface, wherein the first electrode is formed on the top surface. The electrodes are electrically connected to the matrix of column and row control lines on the lower side of the substrate. A gap between adjacent wells of the display substrate matches a gap between adjacent capture positions of the imprint stamp substrate. In this method, the upper surface of the imprint stamp substrate is pressed against the upper surface of the display substrate so that micro light emitting diodes are charged in each capture position, and a plurality of micro light emitting diodes are transferred from the imprint stamp substrate to the micro light emitting diode connection gasket of the display substrate. let it Similarly, in the transition process, the display substrate is heated to promote binding of the electrodes.

The present application further provides an axial micro light emitting diode mass transfer method. The method provides a fluid assembly imprint stamp substrate having a planar top surface, wherein a plurality of capture locations are formed on the top surface, the capture locations having a first peripheral shape, a central portion having a planar first depth, It has a distal portion having a planar second depth, the second depth being less than the first depth, and a proximal portion having a planar second depth. Through fluid assembling process, this method allows axial micro light emitting diodes to be filled in the catching position, and each micro light emitting diode occupying the corresponding catching position is connected to the first peripheral shape, the central part, the main body, and the vertical It has a planar body, wherein the thickness of the body is greater than the first depth but less than twice the first depth. The far end electrode horizontally halves the main body to contact the far end portion of the catching position, and the vertical plane electrode thickness of the far end electrode is greater than the second depth of the catching position but less than twice the second depth. The near-end electrode has the same thickness as the far-end electrode, and horizontally divides the main body into two halves to contact the near-end portion of the capture position.

This method provides a display substrate having a planar upper surface and an array of micro light emitting diode connection gaskets, wherein each micro light emitting diode connection gasket is formed on the upper surface and electrically connected to a matrix of column and row control lines on the lower side. contains electrodes. The display substrate has a gap separating adjacent wells, and the gap matches a gap separating adjacent capture positions on the imprint stamp substrate. In this method, the upper surface of the imprint stamp substrate is pressed against the upper surface of the display substrate, so that each capture position is brought into contact with the corresponding micro light emitting diode, and the micro light emitting diode is transferred from the imprint stamp substrate to the display substrate, usually by heating It should facilitate the binding of the electrodes.

The above-described systems and methods are described in detail below.

1a-1c are a cross-sectional view based on a GaN LED ( FIG. 1a ), a cross-sectional view of two vertical micro light emitting diodes ( FIG. 1b ) and a cross-sectional view of one surface mount micro light emitting diode ( FIG. 1c ) (prior art).
Figure 2a is a process (prior art) of removing a micro light emitting diode from a sapphire growth substrate using a laser ablation technique.
FIG. 2B is a pick-and-place process (prior art) in which a device is moved from a carrier wafer and fixed to a display substrate.
Figure 2c is a process (prior art) of connecting the anode of the micro light emitting diode and the substrate electrode.
3A-3H are steps (prior art) of an exemplary mass transfer process.
4A-4B are examples of covered areas (FIG. 4A) in which imprint pickup is performed using a 14 mm imprint stamp on a 100 mm wafer, with 20% of micro light emitting diodes remaining on the wafer, and also micro light emitting diodes on three imprint stamps. A defect occurs in the light emitting diode (Fig. 4b) (prior art).
5 is a partial cross-sectional view showing a typical backplate arrangement of a surface-mounted micro light emitting diode and a power transistor for controlling the luminance of the micro light emitting diode.
6A to 6B are a plan view and a cross-sectional view of a surface-mounted micro light emitting diode for fluid assembly, respectively.
7 is a schematic diagram of a micro light emitting diode wafer after being selectively picked up.
Figure 8 briefly describes the hydrodynamic effect, and 100% of the micro light emitting diodes can be assembled in the correct direction with the electrodes facing downward.
9A to 9D are steps of using a micro light emitting diode mass transfer imprint system.
10A to 10D are cross-sectional views of a process of transferring a micro light emitting diode from a carrier substrate to a display substrate.
11A to 11D are schematic diagrams of an imprint system, wherein the micro light emitting diode is a vertical micro light emitting diode.
12A-12B are partial cross-sectional views of a suction force generator for assisting in fixing a micro light emitting diode in a captured position on a carrier substrate.
13A to 13K are schematic diagrams of steps of using a micro light emitting diode mass transfer imprint system on a fluid assembly imprint stamp substrate.
14a and 14b are schematic diagrams for helping to fix a micro light emitting diode to a fluid assembly capture position by using an electrostatic power generator and a magnetic force generator as auxiliary devices, respectively.
15A to 15I are schematic diagrams of a micro light emitting diode mass transfer system using fluid imprint and axial micro light emitting diodes.
16 is a flow chart of a micro light emitting diode mass transition method corresponding to the systems shown in FIGS. 9A to 9D.
FIG. 17 is a flow chart of a micro light emitting diode mass transfer method using the fluid assembly imprint stamp substrate shown in FIGS. 13A to 13K.
18 is a flowchart of the axial (lead wire) micro light emitting diode mass transfer method shown in FIGS. 15A to 15I.
19 is a flow chart of an interval expansion method during micro light emitting diode transition.

Hereinafter, in the specific content for carrying out the invention, the present application will be described in detail with reference to the accompanying drawings.

US Patent Nos. 9,825,202 and 10,418,527 have already reported the general process of micro light emitting diode displays using inorganic LEDs and fluid assembly on a display backing, these patents being incorporated herein by reference. In particular, U.S. Pat. No. 9,825,202 describes a process for fabricating a suitable display screen backing starting from column 13, line 26, as shown in FIG. His electrical requirements are described in unpublished US patent application Ser. No. 16/727,186, which patent is also incorporated herein by reference. The display substrate used in FIGS. 14B and 14C has the same row and column arrangement and thin film transistor (TFT) circuit as described in US Patent 9,825,202, but without a well layer. This is because micro light emitting diodes are installed on the mass transfer imprint stamp.

5 is a partial cross-sectional view illustrating an exemplary backplate arrangement of a surface-mounted micro-light emitting diode and a power transistor that controls the luminance of the micro-light emitting diode.

The fluid assembly techniques disclosed in U.S. Patent Nos. 9,825,202, 10,418,527 and 10,543,486 (herein incorporated by reference) are applied to the production of low-cost micro light emitting diode displays that are directly and randomly assembled. Here, one imprint stamp is manufactured using the same assembly technique, and the micro light emitting diodes are sequentially bound to the electrodes of the display substrate. Compared to the direct fluid assembly method, the advantage of this method is that the application of pressure using an imprint stamp during the binding process helps to form an ohmic contact between the micro light emitting diode and the display. As used herein, transfer imprint stamps are installed to have arrayed capture locations, matching the spacing between the capture locations with the spacing between display pixels. The imprint stamp may be made of glass, quartz or monocrystalline silicon, and the capture locations (also referred to as wells) may be etched into the imprint stamp or a layer of film may be deposited on the imprint stamp, for example patterned polyimide. and fabricated by patterning the wells using photolithography. The capture site and the micro light emitting diode have the same shape, which may be slightly larger than that shown in FIG. 8 of US Pat. No. 10,804,426, which is incorporated herein by reference. A unique part of the system according to the present text is that the depth of the capture position can be smaller than at least one point in the thickness of the micro light emitting diode, so that the micro light emitting diode can come into contact with the assembly tool or display board without interference from the upper surface of the imprint stamp. can The wells (captures) etched on the imprint stamp can be made more robust, allowing for more thorough cleaning, but controlling the depth of the captures can be more difficult. Conversely, the depth of the capture sites formed on the polyimide or deposited film can control the thickness of the film, but can be more easily damaged.

The imprint system according to the present application combines micro light emitting diodes of various specifications, but the existing LED structure shown in FIG. It is not possible to accurately position and bind to the display substrate. The disk-shaped surface-mounted micro light emitting diode described in U.S. Patent 10,804,426 is installed as a solution within a certain range and is bound to the fluid assembly described in U.S. Patent 9,825,202, for reasons as shown in column 12, row 56 and FIG. 16, Such a device is applied to the imprint system described in this application. It should be understood herein that other micro light emitting diode shapes, such as square, rectangular and triangular elements, are disclosed in Figure 8 of US Pat. No. 9,825,202 and Figure 4 of US Pat. No. 10,516,084 (incorporated herein by reference) in the same manner. can be used as Likewise, the imprint system is not limited by surface mount micro light emitting diodes. Vertical micro light emitting diodes can also use this method, and after assembling a single bottom electrode, the upper electrode is processed and manufactured. Such changes are obvious to those skilled in the art, and in consideration of brevity, this application will not be further described herein.

6a and 6b show a plan view and a cross-sectional view of a surface-mounted micro light emitting diode for fluid assembly, respectively. The structure of this device typically includes pillars with a diameter of 20 to 100 micrometers (μm), a thickness of 4 to 6 μm, and a height of 5 to 10 μm. In this situation, the well depth is typically 3.5 to 4.5 μm, which is applied to the thickness of the micro light emitting diode. For a detailed manufacturing process, reference may be made to column 8, line 56 and FIG. 6 of US Patent Application Serial No. 10/804,426. The shape of the disc matches the cylindrical shape of the catching position, the depth of the catching position is usually smaller than the thickness of the micro light emitting diode, and its diameter is approximately larger than the diameter of the micro light emitting diode. Surface mount electrodes are usually made of solder such as tin/indium or gold/germanium, and the binding surfaces of the P-connection gasket and the N-connection gasket must be located on the same plane to ensure contact.

7 shows a wafer of micro light emitting diodes after being selectively picked up. Defects are identified through optical microscopy, scanning electron microscopy (SEM) images, cathodoluminescence, or photoluminescence. Its purpose is to identify any defects that can cause display pixel errors, so that defective products can be eliminated from the micro light emitting diode suspension for manufacturing. Combining the defect map with a known pattern, such as edge beads and arrays, yields the known locations of all defective micro light emitting diodes. A printing process is used to cover defective micro light emitting diodes with a capture material to prevent them from being picked up. As shown in the figure, in the process of selectively picking up the imprint stamp, all passed micro light emitting diodes are acquired, leaving defective micro light emitting diodes. One significant advantage of fluid assembly technology is that high availability is used to prevent defective elements from being incorporated and bonded. Selective pick-up methods are described in more detail in the filings of unpublished US patent application Ser. No. 16/875,994, which application is incorporated herein by reference.

After the fabrication of the micro light emitting diode is completed, the growth wafer is attached to the carrier wafer by an adhesive layer, and the micro light emitting diode is peeled off from the sapphire wafer through laser peeling (LLO) technology, thereby forming a pillar on the lower surface of the micro light emitting diode. pattern it

The micro light emitting diode suspension is dispersed on a carrier substrate and assembled according to the description in FIG. 7 of US Patent No. 10,418,527 and US Patent No. 10,804,426. In the mass transfer method, it is very important to prevent surface contaminants from interfering with the exposed surface of the micro light emitting diode and the surface of the target position. Therefore, since any unassembled micro light emitting diodes on the surface are removed and recovered after assembly, an effective cleaning method is also very important.

Figure 8 briefly outlines the hydrodynamic effect, which can assemble 100% of the micro light emitting diodes in the correct direction with the electrodes pointing down. The assembled substrate is inspected. If some wells are not filled, or other defects such as unassembled micro light emitting diodes exist, the micro light emitting diodes can be removed only by washing the imprint stamp with a solvent. The micro light emitting diode may be recovered by capturing the solvent in storage. The blank imprint stamp is further cleaned, dried, and inspected to ensure that there is no surface contamination or residue at the capture location. This function is very important for conventional imprint stamps that use an elastic material or an adhesive to fix micro light emitting diodes, because it is difficult to clean and reuse. In existing technologies, imprint stamps with contaminated or defective micro light emitting diodes are typically discarded, so that complete micro light emitting diodes on the imprint stamp are not recovered.

9A to 9D show the use steps of the micro light emitting diode mass transfer imprint system. The system includes an imprint stamp substrate 900 having a top surface 902 . On the upper surface 902, an array of imprint stamp substrate capture locations 904 are formed. Each catch position 904 is configured as a columnar groove, so that a keel 906 extending from the lower surface 908 of the micro light emitting diode 910 is temporarily fixed. As shown in the figure, the micro light emitting diode 910 is a surface-mounted micro light emitting diode, and each micro light emitting diode 910 includes a planar top surface 912, and the top surface 912 includes a first electrode ( 914) and the second electrode 916 are installed. In this situation, no electricity is conducted to the poles 906. In this particular example, as shown in FIG. 6A, the second electrode is one full ring or a partial ring surrounding the first electrode. In the system of FIGS. 9A-9D or 11A-11D (see below), an adhesive or an elastomer may be used to pattern the imprint stamp substrate top surface 902, whereby the micro light emitting diode is positioned in the capture position. to be attached

The charged carrier substrate 1000 is a basis for mass transfer to the display substrate 918 using the imprint stamp substrate 900, and a single micro light emitting diode is shown in the drawing. Although not clearly shown in the drawing, it is obvious that a micro light emitting diode operates by connecting an electrode connection gasket of a display substrate to a network composed of one matrix line. Please refer to US Patent No. 9,825,202 for specific details. In this situation, the carrier substrate 1000 is a planar surface substrate provided with wells, and local projections (optionally adhesive or elastic material) that are close to the imprint stamp capture locations 904 contact each micro light emitting diode. It can be (as shown in Figure 9b). Since the micro light emitting diode is typically fixed to the carrier only by gravity, the relatively weak adhesive force is removed from the carrier by an optional adhesive or an elastic material in the process of transferring the micro light emitting diode. The imprint stamp is pressed while being aligned with the electrodes on the display substrate, forming rigid contact between the electrodes of the micro light emitting diode and the electrodes on the display substrate, and at the same time heating and binding the solder (FIG. 9c). In another embodiment, the connection may be carried out by a separate ACF film (not shown). When the binding is completed, when the imprint stamp is transferred, it is retrieved and released from the micro light emitting diode (FIG. 9D). The imprint stamp substrate 900 and the carrier substrate 1000 are transferred and washed so that they can be used repeatedly, and the entire area of the display substrate 918 is filled by a cycle operation.

10A to 10D are cross-sectional views describing a transition process of a micro light emitting diode from a carrier substrate to a display substrate. The system includes fluid-assembly carrier substrates 1000a-1000c, which have a planar top surface 1002 and wells 1004 arranged in an array on the carrier substrate top surface 1002, with spacing ( 1006) is provided, and the spacing 1006 matches the spacing of adjacent capture positions on the imprint stamp substrate. The well 1004 of the carrier substrate has a first perimeter shape (circular in this embodiment) and a well bottom surface 1008 that is planar. The surface-mounted micro light emitting diodes 910a to 910c all have a top surface 912 having a first peripheral shape and a flat surface, so that the bottom surface 1008 and the well bottom surface 1008 are formed by the first electrode 914 and the second electrode 916. are contacted (as shown in FIG. 9A).

When RGB is displayed, the imprint system may further include a first fluid-assembly carrier substrate 1000a and array-arranged wells installed on the upper surface of the carrier substrate, with gaps 1006 between adjacent wells and the imprint stamp substrate It matches the capture position of (FIG. 10b). The micro light emitting diodes 910a are configured to emit light of a first wavelength, and each micro light emitting diode occupies a corresponding well in the first carrier substrate 1000a. Similarly, the second fluid-assembly carrier substrate 1000b includes an array of wells installed on the upper surface of the carrier substrate, and has gaps 1006 between adjacent wells to match the captured positions of the imprint stamp substrate. The micro light emitting diodes 910b are configured to emit light of a second wavelength, and each micro light emitting diode occupies a corresponding well in the second carrier substrate 1000b. The third fluid-assembled carrier substrate 1000c includes an array of wells installed on the upper surface of the carrier substrate, and has a gap 1006 between adjacent wells to match the capture position of the imprint stamp substrate. The micro light emitting diodes 910c are configured to emit light of a third wavelength, and each micro light emitting diode occupies a corresponding well in the third carrier substrate 1000c.

In order to manufacture the three colors necessary for the RGB display, assembling and imprinting should be sequentially performed on the three color micro light emitting diodes, as shown in FIGS. 10A to 10D. The design of the array of capture sites on the three carrier substrates is spaced by the spacing 1006 of the display pixels. There is a relatively high possibility that micro light emitting diodes of different colors are determined to have different sizes and/or shapes due to differences in performance of LEDs or process flow of micro light emitting diodes of different colors. For example, a red micro light emitting diode can be made of aluminum indium gallium phosphide (AlInGaP), according to U.S. Patent No. 10,804,426, in this situation, the red micro light emitting diode will be thicker than the GaN-based blue and green devices. can Since blue and green micro light emitting diodes have different quantum efficiencies, and the human visual organ is more sensitive to green light, it is necessary to manufacture blue and green micro light emitting diodes having different emitting areas. An example of this difference is to adjust each carrier substrate to meet the need for correspondingly colored micro light emitting diodes, as shown in FIG. 10A. The imprint stamp substrate 900a captures the arrayed blue micro light emitting diodes 910a from the carrier substrate, moves them onto the display substrate 918, and aligns the imprint stamp 900a with an empty area on the display substrate to generate micro light emission. The diode electrode and the matching electrode on the display board are physically brought into contact (FIG. 10B). The pressure and heater 1010 is for reinforcing the close contact between the electrodes, and the metal material is melted to form solder and bound. 10C and 10D, the green micro light emitting diode 910b and the red micro light emitting diode 910c are transferred and bound in the same way (imprint stamp 900b, imprint stamp 900c). Materials such as gold/germanium-corresponding copper, indium/zinc-corresponding copper, and gold/ACF/copper may be used for the binding between the micro light emitting diode and the connection gasket, for example. If ACF is used, the material of the display electrode can be selected from a wider range, for example Mo/Al/Mo.

The fluid assembly used in this application implements several improvements over the simple imprint process of the prior art:

1) there are no gaps in the array pattern caused by defective or contaminated micro light emitting diodes;

2) selective pickup and fluid assembly fully utilized all complete micro light emitting diodes on one wafer;

3) it is possible to recover micro light emitting diodes from defective carrier substrates in the assembly process to avoid waste;

4) The carrier substrate is manufactured by the distance of the position capture part on the display, and the expansion of the distance can be easily completed.

11A to 11D show an imprint system, wherein the micro light emitting diodes are vertical micro light emitting diodes, and each vertical micro light emitting diode 1100 has a planar top surface with a first electrode 1104. 1102, and a pole 906 that conducts electricity used as a second electrode. In a surface mount micro light emitting diode, the well 1004 of the carrier substrate has a first peripheral shape (eg circular) and a well bottom 1008 that is one plane. Each vertical micro light emitting diode 1100 has both a first peripheral shape and a planar top surface 1102, the top surface 1102 contacting a corresponding well bottom surface 1008 via a first electrode 1104. do.

In the case of relatively small micro light emitting diodes, the same assembling process can also be applied to vertical micro light emitting diodes, unlike surface mount micro light emitting diodes, where there is not enough space to manufacture two electrodes on the same surface. In this situation, the micro light emitting diode is configured to have a single anode electrode on the top surface, and a cathode electrode on the bottom surface is an electrically conductive keel or electroplated gold or copper on the bottom surface. The electrically conductive pillar may be used as a pillar when fluidly assembled on a carrier plate (substrate).

The assembly and binding sequence of vertical micro light emitting diodes with electrically conductive pillars is as follows. After the micro light emitting diode suspension is prepared by the above selective pick-up method and distributed on the surface of a carrier substrate on which wells having display intervals are installed, it is assembled according to a conventional process. The imprint stamp is aligned with the carrier substrate to remove the micro light emitting diodes from the carrier substrate, as shown in FIG. 11A. The charged imprint stamp is aligned with the display substrate, and pressure is applied to form a mechanical contact between the cathode electrode on the micro light emitting diode and the P-connection gasket electrode on the display substrate (as shown in FIG. 11B). After solder is formed and bound using the heater 1010, the imprint stamp is taken out, washed, and reused. An insulating layer 1106, for example polyimide, is for filling the air gap between the micro light emitting diode and the reflective well, to prevent it from being shorted and planarizing the surface to metallize (FIG. 11C). A pillar protrudes from the insulating layer 1106 to form a self-aligned contact point connected to each micro light emitting diode, and a part of the insulating layer may be removed through short plasma etching to improve the contacting effect. As shown in FIG. 11D, a circuit is formed by connecting the conductive column of the micro light emitting diode to Vss (power source) by a patterned metal.

12a and 12b are partial cross-sectional views of a force generator for assisting in fixing a micro light emitting diode in a captured position on a carrier substrate. 12A uses an electrostatic power generator 1200, and FIG. 12B uses a magnetic force generator 1202. Although shown as a surface mount micro light emitting diode, the force generator can also be applied to vertical micro light emitting diodes.

13A-13K illustrate the steps of using a micro light emitting diode mass transfer imprint system on a fluid assembly imprint stamp substrate. To further simplify the assembly process, the carrier substrate can be omitted by directly filling the imprint stamp using fluid assembly. The micro light emitting diode shown in FIG. 6 uses a pillar structure on the lower surface, hereinafter referred to as a fixing mechanism, and the micro light emitting diode is fixed to the electrode at the fluid assembly capture position. In the direct assembling process, since the electrode position must be "upward" in the imprint stamp, the pillar structure is fabricated on the upper surface of the micro light emitting diode, as shown in Fig. 13A. Fluid assembly is performed in a conventional manner, micro light emitting diodes are assembled in an array arrangement at the capture positions, and both the pillar structure and the electrode face upward. The material for fabricating the pillar structure is usually photosensitive polyimide, which can be removed using a solvent or etched using a plasma such as oxygen. After assembling and drying, the posts are removed (as shown in Fig. 13B) so that the electrodes are adhered onto the display substrate. Although the manufacturing method of the imprint stamp is the same as in the above-described embodiment, since the well structure must not necessarily be affected by the removal of the pillar, an organic thin film cannot be used, and in a preferred method, a position capture structure is formed by directly etching on the substrate. let it do Under the action of gravity and van der Waals force, the imprint stamp can accommodate the micro light emitting diodes, and when the imprint stamp is overturned, the micro light emitting diodes fall away from the imprint stamp. Therefore, during heating, transfer assembly and binding must be performed with the surface of the imprint stamp facing upward, and the display substrate is pressed downward on the imprint stamp (FIG. 13C).

The fluid assembly imprint stamp substrate 1300 has a top surface 1302 that is planar. An array of catch locations 1304 are formed on the upper surface 1302 of the imprint stamp substrate, each capture location having a first peripheral shape, depth 1306, and a planar capture location lower surface 1308. Similar to the foregoing embodiment, the first peripheral shape is circular, but the system is not limited to this shape. The micro light emitting diode 910 is installed at the capture position 1304, has a first peripheral shape, a thickness 1310 greater than the capture position depth 1306, a lower surface 1312 in contact with the lower surface 1308, and a second It has one electrode 1316 and a planar upper surface 1314 extending from the capture position and a protective mechanism (see interpretation below). The micro light emitting diode has the same electrical connection as the vertical micro light emitting diode 1100, and the vertical micro light emitting diode 1100 has a second electrode (as shown in FIG. 13d) formed on the lower surface 1312 or a surface-mounted micro light emitting diode. Having the same electrical connection relationship as the light emitting diode 910, the surface-mounted micro light emitting diode 910 includes a first electrode 1316 and a second electrode 1324 formed on a surface 1314 (FIG. 13A and FIG. see 13e).

As shown in FIG. 13A, the fixing mechanism is a pillar 906 formed on the upper surface of the micro light emitting diode, the pillar 906 is a temporary pillar that does not conduct electricity, and the pillar 906 is a micro light emitting diode and a display substrate ( 1315) is removed before contact. Alternatively, as shown in FIGS. 13D and 13E, the fixture can be a column 906 that conducts electricity connected to the first electrode 1316, where in FIG. 13D the micro light emitting diode is a vertical micro light emitting diode. Diode 1100.

In another embodiment, non-conducting pillars are replaced with central pillars that conduct electricity in the direct imprint transfer process. may be used In this situation, the imprint stamp is a simple plate with arrayed catches, the capture spacing equal to the display pixel spacing. In the display substrate 1318, the P-connection gasket electrode is positioned below the N-connection gasket electrode, leaving a space in an electrically conductive column forming an anode electrode in the micro light emitting diode (FIG. 13F). As the process is changed, there may be a situation where there is a difference between the height of the electrically conductive pillar and the depth of the P-connection gasket groove, so it is possible to compensate for this difference by connecting the micro light emitting diode and the display board by installing the ACF 1325. can

Accordingly, the micro light emitting diode in FIG. 13E is a surface-mounted micro light emitting diode 910a, and the display substrate 1318 in FIG. 13F includes grooves 1320 for accommodating electrically conductive pillars 906.

As another example, a mechanism for positioning and fixing micro light emitting diodes in the process of transferring an imprint stamp establishes a preferential connection between conjugated bio molecule pairs (eg, streptavidin-biotin pairs). use As shown in FIG. 13, after going through the LLO, a single layer of thin silicon dioxide film 1326 is deposited on the back side of the device 1312 to fabricate a functionalized micro light emitting diode. After the surface of the micro light emitting diode is exposed to hydrogen ions or a basic compound, it is silanized by acting between amine terminal molecules, for example, 3-aminepropyl-trimethoxysilane. A streptavidin solution is used to wash the surface to bind the streptavidin molecule 1327 with an amine terminus, thereby forming a streptavidin-functionalized micro light emitting diode (as shown in FIG. 13H). Before assembly, a similar treatment can be performed on the capture sites on the transfer imprint stamp using a biotin terminal ligand, or the well bottom surface can be a surface made of gold, which is exposed to the thiolbiotin bifunctional molecule 1322. Bar, as shown in Fig. 13i.

Accordingly, FIGS. 13G-13K show micro light emitting diodes using conjugated biomolecular pairs as "anchors". Here, the first component 1322 including the conjugated biomolecule pair is applied to the lower surface 1308 of the imprint stamp substrate. The micro light emitting diode fixture is a second component 1327 comprising a pair of conjugated biomolecules applied to the underside 1312 of each micro light emitting diode. In the assembly process, the relatively low capture site depth (about 1 μm) makes it relatively easy to remove misdirected micro-light emitting diodes caused by flow disturbances, and the micro-light emitting diodes with correct orientation are chemically captured. It can be bound to the lower surface of the position, and restrains (restrains) a relatively good marker during the capture position. In Fig. 13j, bioconjugation bonds are shown in extremely magnified z scale to illustrate the binding effect. In practice, the binding layer is very thin, so that the display in Fig. 13K is more accurate. The chemical pairing of the exemplified biotin-streptavidin system is replaced, for example, thiol-maleimide and azide-alkyne are replaced, which provides better stability and ease of processing, but the manufacturing sequence is similar.

14A and 14B show the use of an electrostatic power generator 1400 and a magnetic force generator 1402 as aids, respectively, to help secure the micro light emitting diode in a fluid assembly capture position (with or without a length). it is for In Figures 14a and 14b, it is important to note that the fixture may be gravity. Additionally, in FIG. 14A, the anchoring device is a conjugated biomolecule (not shown). In another embodiment (not shown), the force generator in FIG. 14A may be a magnetic force generator, and the force generator in FIG. 14B may be an electrostatic power generator. 14a and 14b only show the fluid assembly imprint stamp substrate, it should be understood, of course, that the force generator can also be used with the grooved imprint stamp substrate in FIGS. 4b-4d and 11a-11b.

Regarding the increase in complexity, some fixing structure may be added to the imprint stamp structure, to prevent the micro light emitting diode from being dislodged from the captive position when the imprint stamp is inverted. Since the fixing mechanism can be removed from the micro light emitting diode after being bound, the binding method using an adhesive does not have an attractive force. By providing a porous layer between the substrate loading surface and the trapping position forming layer, a vacuum condition is introduced into the imprint system, but the liquid of the fluid assembly may flow into the porous layer, making it impossible to proceed with the drying operation. Among the imprint stamps, the most practical structure for fixing the micro light emitting diode is a magnetic force or electrostatic force fixing structure. In electrostatic power fixation, the micro light emitting diode has a surface mount electrode and a dielectric film deposited on the corresponding surface (that is, the lower surface), and the imprint stamp includes a power electrode under the capture position structure. For magnetic fixation, the micro light emitting diode electrode structure may include a magnetic material, for example, nickel, and the imprint stamp may include a permanent magnet or an electric magnet.

Since these fixtures allow switch control at independent points in the array, a defective imprint stamp can be restored using the following process:

1) inspect the imprint stamp to find defective micro light emitting diodes;

2) start the fixture for all good micro light emitting diodes;

3) removing defective micro light emitting diodes by washing;

4) Place and assemble a separate micro light emitting diode suspension.

On the other hand, the imprint stamp may include an optical sensor, and when pressed on the display substrate, activates (simultaneously or sequentially) all the capturing positions electrically connected to the micro light emitting diodes on the imprint stamp. The imprint stamp is connected to the associated drive circuitry and a system, which is to record which micro light emitting diode is complete. Start the fixing device on the imprint stamp, hold the complete micro light emitting diodes in the captured position, and continue assembling until all the micro light emitting diodes are completely measured, as shown in the above process 2) to 4). same. Then proceed with the binding process.

15A-15I show a single micro light emitting diode mass transfer imprint system, which uses a fluid imprint stamp substrate and an axial micro light emitting diode. This mixed fluid assembly mass transfer method can also be applied to axial micro light emitting diodes according to US patent application Ser. No. 16/846,493. In order to reduce the cost and improve the density, the micro light emitting diode is composed of vertical elements, and the light emitting area is 5 * 8 μm, as shown in FIG. 15G. The vane type micro light emitting diode electrode may be electroplated copper or gold. Although the size of the front features is adjustable, their relative shapes are relatively important, allowing for fluid assembly into the orientation determining array.

15A to 15C show manufacturing processes of the axial micro light emitting diode display substrate 1525. The electrodes 1528 are deposited and patterned of an electrically conductive material (eg, molybdenum/copper (Mo/Cu)) to form a connecting gasket for accommodating the cathode and anode of the micro light emitting diode. An electrolyte thin film 1530 is deposited on the electrode, the material of which may be silicon dioxide, silicon nitride (Si ₃ N ₄ ) or polyimide, and is patterned on the electrolyte thin film 1530 to etch the contact opening, as shown in FIG. 15B. It becomes as it is. Using the metal electrode as a hard mask, the body groove 1532 for accommodating the micro light emitting diode body is etched, as shown in FIG. 15B. Finally, an N-connection gasket 1536 and a P-connection gasket 1534 are formed through electrical conduction, sputtering, or evaporation, as shown in FIG. 15C.

In the shape of the axial micro light emitting diode, the manufacturing process of the imprint stamp becomes more complicated, requiring two different depth capture positions. As shown in FIG. 15D, a first groove 1538 is etched into the substrate, and the first groove 1538 has a depth and contour to accommodate the protruding micro light emitting diode body below the axial electrode surface. In FIG. 15E, a second groove 1504 for accommodating the axial electrode is formed through etching. After the second groove is formed in the first groove 1538, it may be made of a thin film material (for example, photolithographic polyimide).

A known complete axial micro light emitting diode suspension is applied onto an imprint stamp and assembled into a micro light emitting diode array (as shown in FIG. 15F). The assembled imprint stamp is inspected, matched with the display board, and then pressed together to bind the electrodes of the LED and the electrodes on the display board (as shown in FIG. 15I). After the binding is completed, the imprint stamp is collected and washed and inspected to be used repeatedly.

Accordingly, the system includes a fluid assembly imprint stamp substrate 1500 having a planar top surface 1502. An array of captured locations 1504 formed on the upper surface 1502 of the imprint stamp substrate has a first peripheral shape (approximately rectangular), a central portion 1506 having a first planar depth 1508, a second planar It includes a distal portion 1510 having a depth 1512, and a proximal portion 1514 having a planar second depth 1512, the second depth 1512 being less than the first depth 1508.

Referring to FIGS. 15F and 15G together, an axial micro light emitting diode 1516 occupies a corresponding capture location 1504 and has the first peripheral shape, and a body 1518 is positioned at the center of the capture location. In contact with portion 1506, vertical planar portion thickness 1520 is greater than capture first depth 1508, but less than twice the capture first depth 1508. The distal electrode 1522 horizontally halves the body 1518 and contacts the distal portion 1510 at the capture position. The distal electrode 1522 has an electrode thickness 1524 in one vertical direction, which is greater than the second depth 1512 of the capture location but less than twice the second depth 1512 of the capture location. The near-end electrode 1526 horizontally bisects the main body 1518 and contacts the near-end portion 1514 at the capture position, and the near-end electrode 1526 has the electrode thickness 1524.

As shown in FIG. 15I, the process of transferring the micro light emitting diodes to the display substrate is similar to the process of FIG. It is brought into contact with an electrode on one display board. Transfer and binding are done by heating the solder when pressure is applied. Optionally, an ACF film (not shown) can be inserted between the corresponding electrodes to realize electrical and mechanical connections, and does not require a metal phase transition.

Although not clearly shown, the imprint stamp substrate of this embodiment may include an electrostatic or magnetic force generator shown in FIGS. 14A and 14B.

FIG. 16 is a flow chart of a micro light emitting diode mass transition method corresponding to the system shown in FIGS. 9A to 9D. For ease of understanding, the method has been described as including a series of steps having numbers, but the numbers do not imply the order of these steps. It should be understood, of course, that certain steps can be skipped and do not have to be concurrent or performed in a strict sequence. However, it is possible to perform this method by following a conventionally numerical sequence of steps. The method begins at step 1600.

Step 1602 provides an imprint stamp substrate having a planar top surface and an array of catch locations formed on the top surface, each capture location consisting of a columnar groove. On the other hand, in step 1603a, the upper surface of the imprint stamp substrate is patterned with an adhesive material or an elastic body. In step 1604, each catch position groove is for receiving a pillar extending from the lower surface of the micro light emitting diode, limiting the pillar of each micro light emitting diode, and in step 1606, the micro light emitting diode is imprinted on a stamp substrate. fixed on top In operation 1606, the micro light emitting diode may be fixed on the imprint stamp substrate using a separate electrostatic force or magnetic force.

On the one hand, the limiting posts of step 1604 include surface mount LEDs with non-conducting posts, which include a planar surface with first and second electrodes. On the other hand, step 1604 confines and connects the poles that conduct electricity to the second electrode, this vertical LED includes a planar surface with the first electrode (ie the pole is the second electrode). .

On the other hand, step 1602 provides an imprint stamp substrate spaced apart from the capture locations. Step 1601a provides a fluid assembly carrier substrate having a planar top surface and a plurality of wells arrayed on the top surface of the carrier substrate, the spacing between adjacent wells matching the spacing between capture locations on the imprint stamp substrate. do. In step 1601b, micro light emitting diodes are filled into the wells of the carrier substrate through a fluid assembly process. Alternatively, step 1601b may fix the micro light emitting diode to the well using electrostatic force or magnetic force. In step 1603b, the upper surface of the imprint stamp substrate is pressed against the upper surface of the carrier substrate, bringing each capture position into contact with the corresponding well, and in step 1603c, the micro light emitting diodes are mass transferred from the carrier substrate onto the imprint stamp substrate. do.

Specifically, step 1601a may provide a carrier substrate, which has a plurality of wells comprising a first peripheral shape and a planar well bottom surface. Next, in step 1601 b, micro light emitting diodes are filled in each well, wherein the surface mounted micro light emitting diodes filled in the wells have a first peripheral shape, a planar top surface in contact with the bottom surface of the well; It includes a first electrode and a second electrode. In another embodiment, a vertical micro light emitting diode filled in a well at step 1601b has a first peripheral shape, a planar top surface in contact with the bottom surface of the well, which includes a first electrode.

When RGB is displayed, the carrier substrate provided in step 1601a,

a first fluid-assembled carrier substrate including a well array installed on an upper surface of the first fluid assembly carrier substrate, wherein a distance between adjacent wells is matched to a gap between adjacent capturing positions on the imprint stamp substrate;

a second fluid-assembly carrier substrate including a well array installed on an upper surface, wherein a distance between adjacent wells is matched with a gap between adjacent capturing positions on the imprint stamp substrate;

A third fluid-assembled carrier substrate including a well array installed on the upper surface, and the distance between adjacent wells matching the interval between adjacent capture positions on the imprint stamp substrate.

includes

Next, the process of filling the wells of the carrier substrate in step 1601b,

charging a well on a first carrier substrate with a first micro light emitting diode, which is configured to emit light of a first wavelength;

charging a well on a second carrier substrate with a second micro light emitting diode, which is configured to emit light of a second wavelength; and

charging wells on a third carrier substrate using a third micro light emitting diode, configured to emit light of a third wavelength;

includes

The process of transferring the micro light emitting diodes from the carrier substrate to the imprint stamp substrate in step 1603c includes transferring the micro light emitting diodes from the first, second, and third carrier substrates onto the corresponding imprint stamp substrates. As shown in FIGS. 10A and 10B , for RGB micro light emitting diodes having different shapes, it is essential to use carrier substrates of different sizes. In addition, if the RGB micro light emitting diodes have the same diameter, micro light emitting diodes of different wavelengths may be charged using one carrier substrate and transferred to the imprint stamp substrate.

Step 1608 provides a display substrate having a planar top surface and an array of micro light emitting diode connection gaskets, each micro light emitting diode connection gasket including electrodes formed on at least the top surface, which have lower column and row control lines. is electrically connected to the matrix of Adjacent connection gaskets on the display substrate have a gap matching the gap between adjacent capture positions on the imprint stamp substrate, and this gap is the same as the gap between adjacent wells on the carrier substrate. In step 1610, the upper surface of the imprint stamp substrate is pressed against the upper surface of the display substrate, so that each catch position is brought into contact with a corresponding micro light emitting diode connection gasket. In step 1612, a mass of micro light emitting diodes is transferred from the imprint stamp substrate onto the micro light emitting diode connection gasket of the display substrate. On the other hand, by heating the display substrate in step 1612, the micro light emitting diode is bound on the micro light emitting diode connection gasket.

When RGB is displayed, the display substrate in step 1608 is used for the first micro light emitting diode, and includes a plurality of connection gaskets for emitting light of a first wavelength; a plurality of connection gaskets used in the second micro light emitting diode to emit light of a second wavelength; and a connection gasket used in the third micro light emitting diode to emit light of a third wavelength. Next, the process of pressing the upper surface of the imprint stamp substrate to the upper surface of the display substrate in step 1610 includes the process of pressing the imprint stamp substrate filled with the first micro light emitting diode, the second micro light emitting diode, and the third micro light emitting diode, respectively. include Each micro light emitting diode of one wavelength may use an imprint stamp substrate, or when all the micro light emitting diodes have a similar shape, micro light emitting diodes of different wavelengths may be charged using the same substrate and transferred to the display substrate. may be

FIG. 17 is a flowchart illustrating a mass transfer method for micro light emitting diodes using the fluid assembly imprint stamp substrate shown in FIGS. 13A to 13K. The method begins at step 1700. Step 1702 provides a fluid assembly imprint stamp substrate having a planar top surface with a catch location installed on the top surface having a first peripheral shape, depth, and a planar capture location bottom surface. In the fluid assembly process, the micro light emitting diode filled in the capture position in step 1704 has a first peripheral shape, a thickness greater than the depth of the capture position, a lower surface in contact with the lower surface of the capture position, and a first electrode. , and has a planar upper surface extending from the catching position. The micro light emitting diode further includes a fixture. In step 1704, a micro light emitting diode having a second electrode on the lower surface may be used, or a surface-mounted micro light emitting diode having a first electrode and a second electrode on the upper surface may be used to charge the captured position. .

Alternatively, providing an imprint stamp substrate during step 1702 includes providing an imprint stamp substrate having spaced apart capture locations. The display substrate provided in step 1706 has a single flat lower surface and arrayed micro light emitting diode connection gaskets, each micro light emitting diode connection gasket including a first electrode formed on the upper surface, which is connected to a lower row and It is electrically connected to the matrix of row control lines. Intervals between adjacent connection gasket locations on the display substrate are matched with intervals between adjacent capture locations on the imprint stamp substrate. In step 1708, the upper surface of the imprint stamp substrate is pressed against the upper surface of the display substrate, so that each catch position is brought into contact with the micro light emitting diode connection gasket. In operation 1710, a large amount of micro light emitting diodes on the imprint stamp substrate are transferred onto the micro light emitting diode connection gasket of the display substrate. Operation 1710 may include a step of binding the micro light emitting diode and the connection gasket of the display substrate by applying a heating method.

On the other hand, in step 1704, a pillar-type fixture formed on the upper surface of the micro light emitting diode is provided, which may be a pillar that conducts electricity connected to the first electrode (FIGS. 13D and 13E), Or it could be a temporary (removable) non-conducting pillar (Fig. 13a). On the other hand, the imprint stamp substrate provided in step 1702 is coated with a first component comprising a conjugated pair of biomolecules on the lower surface of each capture site. Next, the fixture mentioned in step 1704 covers the lower surface of each micro light emitting diode as a second component comprising a pair of conjugated biomolecules. Examples of conjugated biomolecule pairs include biotin-streptavidin, thiol-maleimide and azide-alkyne. An electrostatic force or magnetic force generator may be further installed on the imprint stamp substrate, as shown in FIGS. 14A and 14B.

18 is a flow chart of an axial micro light emitting diode mass transfer method of the system shown in FIGS. 15A-15I. The method begins at step 1800. Step 1802 provides a fluid assembly imprint stamp substrate having a planar top surface, on which a plurality of catch locations are formed, each capture location having a first peripheral shape and a planar first depth. It has a central portion to be formed, a distal portion having a second depth in a plane smaller than the first depth, and a proximal portion having a second depth. In the fluid assembly process, in step 1804, the catch position is filled using axial micro light emitting diodes, and each micro light emitting diode occupies a corresponding capture position to join the body to the first peripheral shape and the central part. and a thickness of the upright body of the body portion greater than the first depth of the catching position but less than twice the first depth. The micro light emitting diode further includes a far end electrode that horizontally bisects the body portion, the far end electrode is bonded to the far end portion of the catching position, and the electrode thickness of the vertical surface of the far end electrode is greater than the second depth of the catching position, less than twice the second depth. The micro light emitting diode further includes a near-end electrode that horizontally bisects the body portion, which is bonded to the near-end portion of the capture position and has an electrode thickness. On the other hand, the imprint stamp electrode may further include an electrostatic power or magnetic force generator, as shown in FIGS. 14A and 14B.

Alternatively, providing an imprint stamp substrate in step 1802 includes providing an imprint stamp substrate having spaced capture locations. In step 1806, a display substrate having a planar top surface and an array of micro light emitting diode connection gaskets is provided, each micro light emitting diode connection gasket including a first electrode and a second electrode formed on the top surface, A plurality of electrodes are electrically connected to the matrix of lower column and row control lines. The display substrate includes a plurality of connection gaskets spaced at intervals, the intervals matching the separation intervals of the capture positions on the imprint stamp substrate. In step 1808, the upper surface of the imprint stamp substrate is pressed against the upper surface of the display substrate, aligning each catch position with the micro light emitting diode connection gasket. In operation 1810, a mass of micro light emitting diodes is transferred from the imprint stamp substrate to the micro light emitting diode connection gasket of the display substrate. What is selectable is that binding between the micro light emitting diode and the display substrate connecting gasket electrode can be promoted by heating.

19 is a flow chart of an interval expansion method for transitioning micro light emitting diodes. The method begins at step 1900. In step 1902, a micro light emitting diode MOCVD wafer is provided, with a first gap between adjacent micro light emitting diodes. Step 1904 emits micro light emitting diodes into the fluid assembly suspension. Step 1906 provides a carrier substrate having an array of wells with a second spacing between adjacent wells, the second spacing being different from the first spacing. Through a fluid assembly process, at step 1908 micro light emitting diodes are filled into the wells of the carrier substrate. In step 1910, an imprint stamp substrate is provided that includes an array of capture locations, wherein adjacent capture locations are spaced apart by a second distance. In step 1912, the top surface of the imprint stamp substrate is pressed against the top surface of the carrier substrate, bringing each capture location into contact with a corresponding well. In step 1914, the micro light emitting diodes are mass transferred from the carrier substrate to the imprint stamp substrate.

In step 1916, a display substrate having an array of micro light emitting diode connection gaskets is provided. Each micro light emitting diode connection gasket includes at least one electrode formed on an upper surface of the micro light emitting diode connection gasket, which is a control line of a lower column and a row. It is electrically connected to the matrix. Positions of adjacent connection gaskets on the display substrate are spaced apart by the second distance. In step 1918, the upper surface of the imprint stamp substrate is pressed against the upper surface of the display substrate, so that the catch position is brought into contact with the corresponding micro light emitting diode connection gasket. In operation 1920, a large amount of micro light emitting diodes are transferred from the imprint stamp substrate to the micro light emitting diode connection gasket of the display substrate. Preferably, the micro light emitting diode and the electrode of the display substrate connection gasket are bound through heating.

On the one hand, step 1906, step 1908, step 1912 and step 1914 are passed, and through a separate step 1911, i.e., using a fluid assembly process, the micro light emitting diode is imprinted on the stamp substrate. Charge directly to the capture position of

In this application, a system and method for mass transition of micro light emitting diodes are provided. The present application has been described with examples of specific LED, carrier substrate and imprint stamp substrate structures. However, this application is not limited by the above examples. Other variations and embodiments of this application may be envisioned by those skilled in the art.

Imprint stamp 900, 900a, 900b, 900c, 1300, 1500
Imprint stamp top surface 902, 1302, 1502
Capture locations 904, 1304, 1504
Pillar 906
908 micro light emitting diode
micro light emitting diode 910
Surface Mount Micro Light Emitting Diodes 910a, 910b, 910c
Micro light emitting diode top surface 912
First electrode 914, 1316
Second electrode 916, 1324
Display board 918, 1315, 1318, 1525
Carrier substrate 1000, 1000a, 1000b, 1000c
Carrier substrate top surface 1002
Well 1004
Interval 1006
1008 if the carrier substrate
Heater 1010
Vertical Micro Light Emitting Diode 1100
Vertical micro light emitting diode top view 1102
Vertical micro light emitting diode first electrode 1104
insulating layer 1106
Constant Power Generator 1200, 1400
Magnet Generator 1202, 1402
depth 1306
If the capture location is 1308
Micro light emitting diode thickness 1310
1312 micro light emitting diode
Micro light emitting diode top surface 1314
Home 1320
Thiol Biotin Bifunctional / First Component 1322
ACF 1325
Silicon Dioxide Film 1326
streptavidin molecule/first component 1327
Central part 1506
First Depth 1508
Fabric 1510
2nd Depth 1512
Near end 1514
Axial Micro Light Emitting Diode 1516
body 1518
body thickness 1520
Far-end electrode 1522
electrode thickness 1524
Proximal Electrode 1526
electrode 1528
Electrolytic thin film 1530
Main body home 1532
P Connection Gasket 1534
N Connection Gasket 1536
First Home 1538

Claims (22)

In the fluid assembly carrier system for mass transfer of micro light emitting diodes,
a fluid assembly carrier substrate having a planar upper surface and an array of collection locations formed on the upper surface of the carrier substrate;
A fluid assembly carrier system according to claim 1 , wherein a concave well is configured to temporarily fix one fluid-deposited micro light emitting diode at each of the collection locations. According to claim 1,
The fluid assembly carrier system of claim 1 , wherein the micro light emitting diode fills a well described on the carrier substrate. According to claim 1,
The fluid assembly carrier system of claim 1 , wherein a distance between adjacent wells on the carrier substrate is less than or equal to a distance between adjacent capture locations on a corresponding mass transfer imprint stamp. According to claim 3,
The mass transfer imprint stamp
an imprint stamp substrate having an upper surface; and
an array of capture locations formed on an upper surface of the imprint stamp substrate;
wherein each capture location is configured to receive one micro light emitting diode that temporarily corresponds to a well on the carrier substrate. According to claim 4,
Each well of the carrier substrate has a planar lower surface;
The carrier system,
A micro light emitting diode filling the well on the carrier substrate and a pillar extending from the lower surface,
Each of the micro light emitting diodes has a lower surface of a corresponding well and an upper surface in contact with each other,
The fluid assembly carrier system of claim 1 , wherein the collection position of the imprint stamp substrate is configured to receive a pole of the light emitting diode. According to claim 1,
The fluid assembly carrier system of claim 1, wherein the carrier substrate does not contain conductive wires and electronic components. According to claim 2,
Each well of the carrier substrate has a planar lower surface;
The micro light emitting diode is a surface-mounted micro light emitting diode,
The fluid assembly carrier system of claim 1 , wherein each said micro light emitting diode comprises a planar upper surface having a first electrode and a second electrode. According to claim 7,
The fluid assembly carrier system of claim 1 , wherein each of the micro light emitting diodes includes one non-conductive post extending from a lower surface of the micro light emitting diode. According to claim 2,
Each well of the carrier substrate has a planar lower surface,
The micro light emitting diode is a vertical micro light emitting diode,
Each of the micro light emitting diodes includes a top surface having a flat surface of a first electrode in contact with a corresponding well of the carrier substrate, and a second electrode positioned on a bottom surface of the micro light emitting diode. system. According to claim 9,
The fluid assembly carrier system, characterized in that the second electrode of each of the micro light emitting diode is a conductive pillar extending from a lower surface of the micro light emitting diode. According to claim 2,
the carrier substrate well has a first peripheral shape;
The fluid assembly carrier system of claim 1 , wherein the micro light emitting diode has the first peripheral shape. According to claim 2,
A first fluid-assembled carrier substrate having an array having wells formed on an upper surface of the first fluid-assembled carrier substrate;
A second fluid-assembled carrier substrate having an array having wells formed on an upper surface of the second fluid-assembled carrier substrate;
A third fluid-assembled carrier substrate having an array having wells formed on an upper surface of the third fluid-assembled carrier substrate;
a plurality of micro light emitting diodes emitting light of a first wavelength installed to fill one corresponding well of the first fluid-assembled carrier substrate;
a plurality of micro light emitting diodes emitting light of a second wavelength installed to fill each corresponding one well of the second fluid-assembled carrier substrate; and
The fluid assembly carrier system comprising a plurality of micro light emitting diodes emitting light of a third wavelength installed to fill each corresponding one well of the third fluid assembly carrier substrate. According to claim 2,
Further comprising a suction force generator located below the carrier substrate, wherein the suction force generator is selected from the group consisting of an electrostatic power generator and a magnetic force generator and is used to temporarily fix the micro light emitting diode to the well of the carrier substrate. Characterized by a fluid assembly carrier system. According to claim 2,
Applying a first component including a conjugated biomolecule pair to the lower surface of each well of the carrier substrate;
Each of the micro light emitting diodes includes an upper surface, and a second component having a conjugated biomolecule pair is applied to the upper surface;
The fluid assembly carrier system of claim 1 , wherein the upper surface is in mutual contact with a lower surface of a corresponding one of the carrier substrate wells. In the micro light emitting diode mass transfer method,
manufacturing micro light emitting diodes on a wafer;
releasing the micro light emitting diode from the wafer into a suspension;
Transferring the micro light emitting diode to the carrier substrate by fluid deposition;
transferring the micro light emitting diode from the carrier substrate to the mass transfer imprint stamp; and
and transferring the micro light emitting diodes from the mass transfer imprint stamp to a display substrate. According to claim 15,
The carrier substrate has a planar upper surface and an array of wells formed on the upper surface of the carrier substrate;
The well is filled with the micro light emitting diode,
The step of transferring the micro light emitting diode from the carrier substrate to the mass transfer imprint stamp,
An upper surface of the mass transfer imprint stamp is pressed against an upper surface of the carrier substrate so that an array of collecting positions of the mass transfer imprint stamp formed on the upper surface of the mass transfer imprint stamp is bonded to micro light emitting diodes corresponding to wells of the carrier substrate. A micro light emitting diode mass transfer method comprising the step of doing. According to claim 16,
the carrier substrate well having a first peripheral shape and a planar bottom surface of the well;
The step of transferring the micro light emitting diode to the carrier substrate by fluid deposition,
and filling the well with micro light emitting diodes having the first peripheral shape. According to claim 16,
spacing between adjacent wells in the well array of the carrier substrate;
wherein the spacing between adjacent collecting positions in the array of collecting positions of the mass transfer imprint stamp is greater than or equal to the spacing between adjacent wells in the array of wells of the carrier substrate. According to claim 15,
Before transferring the micro light emitting diodes to the carrier substrate by fluid deposition, pillars are formed on each of the micro light emitting diodes, and the pillars are extended to an exposed lower surface of the light emitting diodes. mass transfer method. According to claim 19,
wherein the step of transferring the micro light emitting diode from the carrier substrate to the mass transfer imprint stamp comprises configuring a collecting position of the mass transfer imprint stamp to receive a pole of the micro light emitting diode. Light emitting diode mass transfer method. According to claim 15,
Before the step of transferring the micro light emitting diode to the carrier substrate by fluid deposition,
Applying a first component including a conjugated biomolecule pair to the lower surface of the well of the carrier substrate;
A method for mass transfer of micro light emitting diodes, characterized in that applying a second component having a pair of biomolecules conjugated to the micro light emitting diodes in the suspension. According to claim 15,
Before the step of transferring the micro light emitting diode to the carrier substrate by fluid deposition,
A suction force generator located below the carrier substrate is used, and the suction force generator is selected from the group consisting of an electrostatic power generator and a magnetic force generator and is used to temporarily fix the micro light emitting diode to a well of the carrier substrate. Micro light emitting diode mass transfer method.

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